Reverse osmosis membrane having coral-like structure, and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of membrane separation, and specifically relates to a reverse osmosis membrane having a coral-like structure, and a preparation method therefor and a use thereof. The reverse osmosis membrane comprises a base membrane and a separation layer which are arranged in sequence, wherein the micro-morphology of the separation layer simultaneously comprises a coral-like structure, a nodular structure, and a leaf-like structure. The preparation method comprises: immersing a base membrane in an aqueous phase solution, taking out and draining the residual solution on the surface; and then immersing the drained base membrane in an organic phase solution to undergo an interfacial polymerization reaction, and carrying out heat treatment after draining the residual solution on the surface. The aqueous phase solution comprises a polyamine monomer and water; and the organic phase solution comprises a polyacyl chloride monomer, an alkane solvent, and a co-solvent.

Description

A reverse osmosis membrane with a coral-like structure, its preparation method and application Technical Field

[0001] This invention relates to the field of membrane separation technology, specifically to a reverse osmosis membrane with a coral-like structure, its preparation method, and its application. Background Technology

[0002] Reverse osmosis membranes are one of the most important types of separation membranes used in water treatment processes, and are currently widely used in seawater / brackish water desalination, ultrapure water production, and wastewater treatment. A typical reverse osmosis membrane structure consists of a bottom layer of polyester nonwoven fabric, a middle layer of polysulfone ultrafiltration membrane, and an upper separation layer. It is generally believed that the separation layer determines the membrane's separation performance and contributes the majority of the mass transfer resistance. Therefore, optimizing the separation layer structure has always been a research hotspot. While ensuring a high rejection rate, increasing the flux is crucial for improving the efficiency of reverse osmosis processes, reducing their cost, and expanding their application range.

[0003] Introducing a co-solvent into the organic phase is a commonly used method to optimize the structure of reverse osmosis membranes. A typical reverse osmosis membrane is formed by the interfacial polymerization of trimesoyl chloride and m-phenylenediamine on a polysulfone surface. During the formation of the reverse osmosis membrane, the interfacial polymerization reaction occurs on the organic phase side of the two-phase interface. Adjusting the diffusion rate of m-phenylenediamine from the aqueous phase to the organic phase can modify the structure of the polyamide. Introducing a co-solvent into the organic phase enhances the miscibility between the aqueous and organic phases, thereby promoting the diffusion rate of m-phenylenediamine monomers into the organic phase. Currently available organic phase co-solvents include ethyl acetate, γ-valerolactone, dimethyl carbonate, and ethyl silicate (CN114950165A, CN111569675A, CN109985531A). The addition of these co-solvents causes the morphology of the reverse osmosis membrane separation layer to evolve from a typical tightly packed "nodular" structure to a larger "leaf-like" structure, thereby increasing the water flux of the reverse osmosis membrane. However, these traditional co-solvents have limited effect on increasing the permeate flux of reverse osmosis membranes, and further increasing the flux leads to a decrease in salt rejection. In order to significantly increase the water flux of reverse osmosis membranes without reducing their salt rejection, it is necessary to further optimize the structure and preparation method of reverse osmosis membranes. Summary of the Invention

[0004] The primary objective of this invention is to provide a reverse osmosis membrane with a coral-like structure, which can significantly increase the water flux of the reverse osmosis membrane without reducing the salt rejection rate.

[0005] The second objective of this invention is to provide a method for preparing a reverse osmosis membrane with a coral-like structure, which is simple and easy to implement.

[0006] The third objective of this invention is to provide an application of a reverse osmosis membrane with a coral-like structure, which has broad application prospects.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A reverse osmosis membrane with a coral-like structure includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0009] The reverse osmosis membrane obtained by this invention contains a "coral-like" structure composed of multiple layers (≥2 layers) of spherical particles. These spherical particles have an outer diameter of 20-150 nm and possess a hollow or non-hollow structure. The wall thickness of the spherical particles (i.e., the intrinsic thickness of the "coral-like" structure) is 10-60 nm, and the maximum apparent thickness of the "coral-like" structure is 20-1000 nm. The coral-like structure of the reverse osmosis membrane of this invention increases the effective surface area of ​​the reverse osmosis membrane, increases water transport channels, and reduces water transport resistance, thereby significantly improving the water flux of the reverse osmosis membrane without reducing its salt rejection rate.

[0010] Furthermore, the area of ​​the coral-like structure accounts for 0.001%-99.999% of the total surface area of ​​the separation membrane.

[0011] Furthermore, the area of ​​the coral-like structure accounts for 3%-80% of the total surface area of ​​the separation membrane.

[0012] The permeation membrane obtained by the present invention has a multiple structure. The area of ​​the region containing the "coral" structure in the multiple structure accounts for 0.001% to 99.999% of the total surface area of ​​the separation membrane, preferably 3%-80%. In the preferred embodiment of the present invention, the area of ​​the "coral" structure accounts for 5%-60% of the total surface area of ​​the separation membrane.

[0013] The method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure includes the following steps:

[0014] The base film is immersed in an aqueous solution, then removed and drained of any residual solution. It is then immersed in an organic solution to carry out interfacial polymerization. After draining of any residual solution, it is subjected to heat treatment.

[0015] The aqueous phase solution comprises polyamine monomers and water; the organic phase solution comprises polyacrylamide monomers, alkane solvents, and novel cosolvents.

[0016] The organic phase solution of the present invention includes an acyl chloride monomer, an alkane solvent, and a novel co-solvent. The combination of the alkane solvent and the novel co-solvent enables the prepared reverse osmosis membrane to possess multiple structures, including "coral-like," "leaf-like," and "nodular" structures.

[0017] Furthermore, the concentration of the novel cosolvent in the organic phase solution is 0.01-50 wt%; the novel cosolvent is selected from one or two of ester compounds and ether compounds; the ester compounds all contain two or more ester functional groups and the carbon-oxygen ratio of the compound molecules is ≥2.5; the carbon-oxygen ratio of the ether compound molecules is ≥8.

[0018] By controlling the ratio of alkane solvent to novel co-solvent through the above technical solutions, the area of ​​the "coral-like" region in the separation layer accounts for 0.001% to 99.999% of the area on the separation membrane surface, preferably 3%-80%. In the preferred embodiment of the present invention, the area of ​​the "coral-like" region accounts for 5%-60% of the area on the separation membrane surface.

[0019] Further, the ester compounds include, but are not limited to, those selected from dibutyl oxalate, diisobutyl oxalate, dipentyl oxalate, diisopentyl oxalate, dibutyl malonate, diisobutyl malonate, dipentyl malonate, diisopentyl malonate, dibutyl succinate, diisobutyl succinate, dipentyl succinate, diisopentyl succinate, diisopentyl fumarate, diisobutyl fumarate, dipentyl fumarate, diisopentyl fumarate, dibutyl maleate, diisobutyl maleate, dipentyl maleate, diisopentyl maleate, dipropyl maleate, diisopropyl maleate, dibutyl glutarate, diisopropyl glutarate, dibutyl glutarate, diisobutyl glutarate, dipentyl glutarate, diisobutyl glutarate, dipentyl glutarate, glutaric acid. The ether compounds are selected from one or more of the following: diisoamyl adipate, diethyl adipate, dipropyl adipate, diisopropyl adipate, dibutyl adipate, diisobutyl adipate, dipentyl adipate, and diisoamyl adipate; or from one or more carbon chain isomers of the ester compounds. The ether compounds include, but are not limited to, one or more of the following: phenethyl ether, n-butylphenyl ether, isobutylphenyl ether, n-pentylphenyl ether, isopentylphenyl ether, n-hexylphenyl ether, isohexylphenyl ether, diphenyl ether, dibutyl ether, diisobutyl ether, dipentyl ether, diisopentyl ether, dihexyl ether, and diisohexyl ether; or from one or more carbon chain isomers of the ether compounds.

[0020] Further, the concentration of the polyacrylamide monomer in the organic phase solution is 0.01-5 wt%; the polyacrylamide monomer is selected from one or more of pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid chloride, biphenyl tricarboxylic acid chloride, biphenyl tetracarboxylic acid chloride, naphthalene dicarboxylic acid chloride, naphthalene tricarboxylic acid chloride, naphthalene tetracarboxylic acid chloride, malonyl chloride, succinic acid chloride, glutaryl chloride, and adipyl chloride; further, the concentration of the polyamine monomer in the aqueous phase solution is 0.5-5 wt%; the polyamine monomer includes, but is not limited to, one or more of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, diaminotoluene, ethylenediamine, propylenediamine, butanediamine, diaminocyclohexane, and piperazine.

[0021] Furthermore, the interfacial polymerization reaction takes 1-300 seconds; the heat treatment temperature is 40-150°C, and the heat treatment time is 0.1-10 minutes.

[0022] Furthermore, the alkane solvent includes, but is not limited to, one or more of hexane, heptane, octane, nonane, decane, undecane, dodecane, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, and Isopar M; the base membrane is a porous membrane; the material of the porous membrane includes, but is not limited to, one of polysulfone, polyethersulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polyimide, polyetherimide, polyacrylonitrile, polyphenylene ether, polyphenylene sulfide, polyetherketone, and polyaryletherketone.

[0023] Furthermore, the aqueous solution also includes triethylamine and camphor sulfonic acid; the concentration of triethylamine in the aqueous solution is 0.5-3 wt%, and the concentration of camphor sulfonic acid in the aqueous solution is 1-5 wt%.

[0024] The above-mentioned reverse osmosis membranes with coral-like structures are used in the field of water treatment.

[0025] The beneficial technical effects of this invention are as follows:

[0026] 1. This invention provides a reverse osmosis membrane with a coral-like structure. The reverse osmosis membrane simultaneously possesses multiple structures, including "coral-like," "leaf-like," and "nodular" structures. The "coral-like" structure is composed of multiple layers (≥2 layers) of stacked spherical particles. These spherical particles have an outer diameter of 20-150 nm and possess a hollow or non-hollow structure. The wall thickness of the spherical particles (i.e., the intrinsic thickness of the "coral-like" structure) is 10-60 nm, and the apparent thickness of the "coral-like" structure is 20-1000 nm. The area of ​​the "coral-like" structure accounts for 0.001%-99.999% of the total surface area of ​​the separation membrane. The coral-like structure of the reverse osmosis membrane can increase the effective surface area of ​​the membrane, increase water transport channels, and reduce water transport resistance, thereby significantly improving the water flux of the reverse osmosis membrane without reducing its salt rejection rate.

[0027] 2. This invention provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The organic phase solution used in the preparation process includes an acyl chloride monomer, an alkane solvent, and a novel co-solvent. The combination of the alkane solvent and the novel co-solvent enables the prepared reverse osmosis membrane to simultaneously possess multiple structures such as "coral-like," "leaf-like," and "nodular." Furthermore, by controlling the types and proportions of the alkane solvent and the novel co-solvent, the proportion of the "coral-like" structure area in the total surface area of ​​the separation membrane can be controlled.

[0028] 3. The preparation method of the coral-like reverse osmosis membrane of the present invention is simple and easy to mass-produce. Attached Figure Description

[0029] Figure 1 shows scanning electron microscope (SEM) images of the reverse osmosis membrane samples obtained in Comparative Example 1 and Examples 1-4, respectively. In the figure, A is a SEM image magnified 1000 times, and B and C are SEM images magnified 50000 times.

[0030] Figure 2 shows scanning electron microscope (SEM) images of the surface of the separation layer of the reverse osmosis membrane samples obtained in Comparative Example 1, Example 2, and Example 4, and transmission electron microscope (TEM) images of their cross sections, respectively. The magnification of Figures A1-A3 is 50,000, and A1-A3 represent the surface appearances of the "nodular", "leaf-like", and "coral-like" structures, respectively. The magnification of Figures B1-B3 is 30,000, and B1-B3 represent the cross-sectional appearances of the "nodular", "leaf-like", and "coral-like" structures, respectively. Detailed Implementation

[0031] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels. Example Example 1

[0032] This embodiment provides a reverse osmosis membrane with a coral-like structure, which includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0033] This embodiment also provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The specific preparation steps are as follows:

[0034] Immerse the polysulfone porous membrane in an aqueous solution for 10 seconds, remove it and drain off any residual solution on the surface; then immerse it in an organic solution for interfacial polymerization for 10 seconds, drain off any residual solution on the surface, and then heat-treat the membrane at 90°C for 8 minutes.

[0035] The aqueous phase solution consists of 3 wt% m-phenylenediamine, 1.9 wt% triethylamine, 3.3 wt% camphor sulfonic acid and water;

[0036] The organic phase solution consisted of 0.21 wt% pyromellitic acid chloride, 5 wt% diisobutyl fumarate, and Isopar G. Example 2

[0037] This embodiment provides a reverse osmosis membrane with a coral-like structure, which includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0038] This embodiment also provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The specific preparation steps are as follows:

[0039] Immerse the polysulfone porous membrane in an aqueous solution for 10 seconds, remove it and drain off any residual solution on the surface; then immerse it in an organic solution for interfacial polymerization for 20 seconds, drain off any residual solution on the surface, and then heat-treat the membrane at 85°C for 6 minutes.

[0040] The aqueous phase solution consists of 2 wt% m-phenylenediamine, 1 wt% triethylamine, 3 wt% camphor sulfonic acid, and water.

[0041] The organic phase solution consists of a mixture of 0.1 wt% trimesoyl chloride and terephthaloyl chloride, 10 wt% diisobutyl fumarate, and Isopar L; the ratio of trimesoyl chloride to terephthaloyl chloride is 5:1. Example 3

[0042] This embodiment provides a reverse osmosis membrane with a coral-like structure, which includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0043] This embodiment also provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The specific preparation steps are as follows:

[0044] The polyethersulfone porous membrane was immersed in an aqueous solution for 10 seconds, then removed and drained of any residual solution. It was then immersed in an organic solution for interfacial polymerization for 30 seconds, drained of any remaining solution, and finally heat-treated at 95°C for 5 minutes. The aqueous solution consisted of a mixture of 4 wt% m-phenylenediamine and o-phenylenediamine, 2 wt% triethylamine, 4 wt% camphor sulfonic acid, and water, with a m-phenylenediamine to o-phenylenediamine ratio of 5:1.

[0045] The organic phase solution consists of 0.3 wt% pyromellitic acid chloride, 5 wt% dibutyl fumarate, and n-dodecane. Example 4

[0046] This embodiment provides a reverse osmosis membrane with a coral-like structure, which includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0047] This embodiment also provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The specific preparation steps are as follows:

[0048] Immerse the polysulfone porous membrane in an aqueous solution for 10 seconds, remove it and drain off any residual solution on the surface; then immerse it in an organic solution for interfacial polymerization for 10 seconds, drain off any residual solution on the surface, and then heat-treat the membrane at 90°C for 6 minutes.

[0049] The aqueous phase solution consists of 3 wt% m-phenylenediamine, 1.9 wt% triethylamine, 3.3 wt% camphor sulfonic acid and water;

[0050] The organic phase solution consisted of 0.21 wt% trimesoyl chloride, 10 wt% dibutyl fumarate, and Isopar G. Example 5

[0051] This embodiment provides a reverse osmosis membrane with a coral-like structure, which includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0052] This embodiment also provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The specific preparation steps are as follows:

[0053] Immerse the polysulfone porous membrane in an aqueous solution for 10 seconds, remove it and drain off any residual solution on the surface; then immerse it in an organic solution for interfacial polymerization for 10 seconds, drain off any residual solution on the surface, and then heat-treat the membrane at 90°C for 6 minutes.

[0054] The aqueous phase solution consists of 3 wt% m-phenylenediamine, 1.9 wt% triethylamine, 3.3 wt% camphor sulfonic acid and water;

[0055] The organic phase solution consisted of 0.21 wt% pyromellitic acid chloride, 4 wt% dibutyl succinate, and Isopar G. Example 6

[0056] This embodiment provides a reverse osmosis membrane with a coral-like structure, which includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0057] This embodiment also provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The specific preparation steps are as follows:

[0058] Immerse the polysulfone porous membrane in an aqueous solution for 10 seconds, remove it and drain off any residual solution on the surface; then immerse it in an organic solution for interfacial polymerization for 10 seconds, drain off any residual solution on the surface, and then heat-treat the membrane at 90°C for 6 minutes.

[0059] The aqueous phase solution consists of 3 wt% m-phenylenediamine, 1.9 wt% triethylamine, 3.3 wt% camphor sulfonic acid and water;

[0060] The organic phase solution consisted of 0.21 wt% pyromellitic acid chloride, 4 wt% phenethyl ether, and Isopar G. Example 7

[0061] This embodiment provides a reverse osmosis membrane with a coral-like structure, which includes a base membrane and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

[0062] This embodiment also provides a method for preparing the above-mentioned reverse osmosis membrane with a coral-like structure. The specific preparation steps are as follows:

[0063] Immerse the polysulfone porous membrane in an aqueous solution for 10 seconds, remove it and drain off any residual solution on the surface; then immerse it in an organic solution for interfacial polymerization for 10 seconds, drain off any residual solution on the surface, and then heat-treat the membrane at 90°C for 6 minutes.

[0064] The aqueous phase solution consists of 3 wt% m-phenylenediamine, 1.9 wt% triethylamine, 3.3 wt% camphor sulfonic acid and water;

[0065] The organic phase solution consisted of 0.21 wt% pyromellitic acid chloride, 4 wt% n-butylphenyl ether, and Isopar G.

[0066] Comparative Example

[0067] Comparative Example 1

[0068] The difference between Comparative Example 1 and Example 1 is that the organic phase solution consists of 0.21 wt% pyromellitic acid chloride and Isopar G, and the preparation conditions are the same as those in Example 1.

[0069] Test case

[0070] Experimental Example 1

[0071] The surface morphology of the reverse osmosis membrane samples obtained in Comparative Example 1 and Examples 1-4 was observed using field emission scanning electron microscopy, and the results are shown in Figure 1.

[0072] Figure 1 shows scanning electron microscope (SEM) images of the reverse osmosis membrane samples obtained in Comparative Example 1 and Examples 1-4. A0-4 correspond to Comparative Example 1 and Examples 1-4, respectively. Image A in the figure is a 1000x SEM image, while images B and C are 50000x SEM images.

[0073] As shown in Figure 1, Comparative Example 1 exhibits a uniform and flat surface morphology (A0) at a magnification of 1000x. Further magnification reveals nodular structures and a small number of leaf-like structures (B0 and C0). In contrast, the reverse osmosis membrane samples obtained in Examples 1-4 show a non-uniform surface morphology at a magnification of 1000x, including relatively flat areas and areas with irregular protrusions (A1-4). Further magnification of these two areas to 50,000x reveals "nodular" or "leaf-like" structures (C1-4) and a novel "coral-like" structure (B1-4), respectively. The "coral-like" structure areas are marked with circles.

[0074] Experimental Example 2

[0075] The cross-sectional structure of the reverse osmosis membrane sample slices obtained in Comparative Example 1, Example 2, and Example 4 was observed using transmission electron microscopy. The procedure is as follows:

[0076] Before testing, the reverse osmosis membrane samples obtained from Comparative Example 1, Example 2, and Example 4 were embedded in resin and cured at 60°C for 24 hours. Then, they were ultra-thinly sectioned using an ultrathin slicer. Finally, the obtained ultra-thin sections were placed on a special copper grid for observation, as shown in Figure 2.

[0077] Figure 2 shows scanning electron microscope (SEM) images of the surface of the separation layer of the reverse osmosis membrane samples obtained in Comparative Example 1, Example 2, and Example 4, and transmission electron microscope (TEM) images of their cross sections, respectively. The magnification of Figures A1-A3 is 50,000, and A1-A3 represent the surface appearances of the "nodular", "leaf-like", and "coral-like" structures, respectively. The magnification of Figures B1-B3 is 30,000, and B1-B3 represent the cross-sectional appearances of the "nodular", "leaf-like", and "coral-like" structures, respectively.

[0078] Experimental Example 3

[0079] I. The cross-sectional structure of the reverse osmosis membrane sample slices obtained in Examples 1-7 and Comparative Example 1 was observed using a transmission electron microscope. TEM images at 30,000 magnification were selected. The intrinsic and apparent thickness of the membrane structures obtained in Examples 1-7 and Comparative Example 1 were analyzed using Adobe Photoshop software. The specific steps are as follows: a. Scale bar > Measurement (pixels of the original scale bar length); b. Image > Analysis > Set measurement scale > Custom (pixel length, logical length, and logical units); c. Measure thickness (calculate the average and standard deviation of 5 groups). The results are shown in Table 1.

[0080] II. The surface of the reverse osmosis membrane samples obtained in Examples 1-7 and Comparative Example 1 was observed using a field emission scanning electron microscope. SEM images at 1000x magnification were selected, and the area of ​​the "coral structure" region was analyzed using ImageJ software. The specific steps are as follows: ① Image > Type > 8-bit; ② Image > Adjust > Brightness / contrast; ③ Process > Smooth (approximately 5 times); ④ Adjust > Threshold (adjust until all "coral structures" are just included), thus obtaining the area ratio of the "coral structure" region. The results are shown in Table 1.

[0081] Table 1

[0082] As can be seen from Table 1, the addition of the novel cosolvent in the organic phase caused the separation layer to produce leaf-like and "coral-like" structures, and the intrinsic thickness and apparent thickness of the polyamide layer both increased.

[0083] Test Example 4

[0084] The reverse osmosis membrane samples obtained in Examples 1-7 and Comparative Example 1 were tested for performance. The feed solution was a sodium chloride aqueous solution of 32,000 ppm. The membranes were pre-pressurized at 25°C and 5.5 MPa for 3 hours. The water flux and salt rejection rate of each group of membrane samples were tested after 20 minutes. The results are shown in Table 2.

[0085] Table 2

[0086] Membrane Sample Water Flux (LMH) NaCl Retention Rate Example 1 55 99.68% Example 2 66 99.66% Example 3 55 99.69% Example 4 61 99.67% Example 5 60 99.68% Example 6 54 99.71% Example 7 55 99.73% Comparative Example 1 40 99.66%

[0087] As can be seen from Table 2, compared with Comparative Example 1, the reverse osmosis membrane samples obtained in Examples 1-7 of the present invention significantly improved the water flux of the reverse osmosis membrane without reducing its NaCl rejection rate.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A reverse osmosis membrane having a coral-like structure, characterized by, It includes a base film and a separation layer arranged sequentially; the microstructure of the separation layer includes coral-like structure, nodular structure and leaf-like structure.

2. The reverse osmosis membrane having a coral-like structure according to claim 1, wherein, The area of ​​the coral-like structure accounts for 0.001%-99.999% of the total surface area of ​​the separation membrane.

3. The reverse osmosis membrane having a coral-like structure according to claim 2, wherein, The area of ​​the coral-like structure accounts for 3%-80% of the total surface area of ​​the separation membrane.

4. The method for preparing the reverse osmosis membrane with a coral-like structure as described in claim 1, characterized in that, Includes the following steps: Immerse the base membrane in the aqueous solution, then remove it and drain off any residual solution from the surface. Then immerse it in an organic phase solution to carry out interfacial polymerization reaction, drain off the residual solution on the surface, and then perform heat treatment. The aqueous phase solution comprises polyamine monomers and water; the organic phase solution comprises polyacrylamide monomers, alkane solvents, and novel cosolvents.

5. The method for preparing the reverse osmosis membrane with a coral-like structure according to claim 4, characterized in that, The concentration of the novel cosolvent in the organic phase solution is 0.01-50 wt%; the novel cosolvent is selected from one or two of ester compounds and ether compounds; the ester compounds all contain two or more ester functional groups and the carbon-oxygen ratio of the compound molecules is ≥2.5; the carbon-oxygen ratio of the ether compound molecules is ≥8.

6. The method for preparing the reverse osmosis membrane with a coral-like structure according to claim 5, characterized in that, The ester compounds are selected from dibutyl oxalate, diisobutyl oxalate, dipentyl oxalate, diisopentyl oxalate, dibutyl malonate, diisobutyl malonate, dipentyl malonate, diisopentyl malonate, dibutyl succinate, diisobutyl succinate, dipentyl succinate, diisopentyl succinate, diisopentyl succinate, dibutyl fumarate, diisobutyl fumarate, dipentyl fumarate, diisopentyl fumarate, dibutyl maleate, diisobutyl maleate, dipentyl maleate, diisopentyl maleate, dipropyl maleate, diisopropyl maleate, dibutyl glutarate, diisopropyl glutarate, dibutyl glutarate, diisobutyl glutarate, diisobutyl glutarate, dipentyl glutarate, diisobutyl glutarate, diisobutyl glutarate, diisobutyl glutarate, diisobutyl glutarate, diisobutyl glutarate, diisobutyl glutarate The ether compound is selected from one or more of the following: pentyl ester, diethyl adipate, dipropyl adipate, diisopropyl adipate, dibutyl adipate, diisobutyl adipate, dipentyl adipate, and diisopentyl adipate; or selected from one or more carbon chain isomers of the ester compounds.

7. The method for preparing the reverse osmosis membrane with a coral-like structure according to claim 4, characterized in that, The concentration of the polyacrylamide monomer in the organic phase solution is 0.01-5 wt%; the polyacrylamide monomer is selected from one or more of pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid chloride, biphenyl tricarboxylic acid chloride, biphenyl tetracarboxylic acid chloride, naphthalene dicarboxylic acid chloride, naphthalene tricarboxylic acid chloride, naphthalene tetracarboxylic acid chloride, malonyl chloride, succinic acid chloride, glutaryl chloride, and adipyl chloride; the concentration of the polyamine monomer in the aqueous phase solution is 0.5-5 wt%; the polyamine monomer is selected from one or more of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, diaminotoluene, ethylenediamine, propylenediamine, butanediamine, diaminocyclohexane, and piperazine.

8. The method for preparing the reverse osmosis membrane with a coral-like structure according to claim 4, characterized in that, The interfacial polymerization reaction takes 1-300 seconds; the heat treatment temperature is 40-150°C and the heat treatment time is 0.1-10 minutes.

9. The method for preparing the reverse osmosis membrane with a coral-like structure according to claim 4, characterized in that, The alkane solvent is selected from one or more of hexaane, heptane, octane, nonane, decane, undecane, dodecane, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, and Isopar M; the base membrane is a porous membrane; the material of the porous membrane is selected from one of polysulfone, polyethersulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polyimide, polyetherimide, polyacrylonitrile, polyphenylene ether, polyphenylene sulfide, polyetherketone, and polyaryletherketone.

10. The application of the reverse osmosis membrane with a coral-like structure as described in claim 1 in the field of water treatment.

Images